This invention pertains to a structure for storage of grain or other particulate material, such material possessing internal friction characteristics and having an angle of repose.
In the present context, the angle of repose is the maximum angle with the horizontal at which angle a particulate material will retain its position without starting to slide. Although the angle of repose varies with such factors as the distribution of fine and coarse particles of the particulate material and its moisture content, it is useful to refer to nominal or typical values for the angles of repose of different materials. As an example, the angle of repose of corn has a nominal or typical value of about 22.degree.. The angles of repose of most types of grain have nominal or typical values of less than about 30.degree.. Each reference to an angle of repose of any particulate material, hereinafter, is intended to refer to the nominal or typical value of the angle of repose of the particulate material.
It is known to store grain or other particulate material within a variety of storage structures including silos with cylindrical walls of circular cross-sections and rectangular buildings. Typically, when grain or other particulate material is stored within a rectangular building having a flat roof or a roof with a canopy sloping at an angle less than the angle of repose of such particulate material, horizontal forces imposed by a pile of such particulate material reaching outer walls of the building are borne by those walls, not by the structural system which supports the canopy of the roof or by the canopy itself.
As increased capacity to store grain or other particulate material has been sought, heretofore, it has been conventional to provide a longer or wider building or a building with higher walls capable of bearing horizontal forces imposed by a pile of such particulate material reaching those walls. If a building of a type used conventionally to store grain or other particulate material had a roof with a canopy sloping at an angle more than the angle of repose of grain or other particulate material stored in a pile within the building, and if the pile were to accumulate to heights reaching the canopy, the pile would impose horizontal forces on the canopy, which would be most likely unable to bear such forces without distortion or rupture.
This invention fills a need, therefore, for an improved structure for storage of grain or other particulate material.